Effect of the structural changes, electrical conductivity, and dielectric properties on the addition of a third glass-former, GeO 2 , to the borophosphate glasses, 40Li 2 O−10B 2 O 3 −(50 − x)P 2 O 5 −xGeO 2 , x = 0−25 mol %, has been studied. Introduction of GeO 2 causes the structural modifications in the glass network, which results in a continuous increase in electrical conductivity. Glasses with low GeO 2 content, up to 10 mol %, show a rapid increase in dc conductivity as a result of the interlinkage of slightly depolymerized phosphate chains and negatively charged [GeO 4 ] − units, which enhances the migration of Li + ions. The Li + ions compensate these delocalized charges connecting both phosphate and germanium units, which results in reduction of both bond effectiveness and binding energy of Li + ions and therefore enables their hop to the next charge-compensating site. For higher GeO 2 content, the dc conductivity increases slightly, tending to approach a maximum in Li + ion mobility caused by the incorporation of GeO 2 units into phosphate network combined with conversion of GeO 4 to GeO 6 units. The strong cross-linkage of germanium and phosphate units creates heteroatomic P−O−Ge bonds responsible for more effectively trapped Li + ions. A close correspondence between dielectric and conductivity parameters at high frequencies indicates that the increase in conductivity indeed is controlled by the modification of structure as a function of GeO 2 addition.
Purpose -To investigate the properties of coatings containing various types of fillers from the point of view of their physical-mechanical properties and anticorrosive properties. Design/methodology/approach -Research used fillers of different types varying in morphology and/or chemical composition; these were then compared with selected pigments and zinc phosphate, an anticorrosive pigment. The following parameters were observed for all of the fillers and pigments: oil absorption, CPVC value, density, extract pH, specific surface, particle size, and water-soluble substances. The morphology of particles was observed by means of an electron-scanning microscope. The coatings of these fillers and pigments were formulated on an epoxy resin binder basis cured with a polyamine hardener. The coatings prepared were subjected to the measurement of physical-mechanical properties such as hardness and deepening resistance, flex resistance, adhesion to steel, and the gloss of the coatings. The coatings containing the fillers and pigments studied underwent corrosion tests in a condenser chamber and in a salt-spray cabinet. Findings -The results obtained through the tests allowed the selection of the optimum filler for an epoxy coating with barrier anticorrosive properties. As per respective findings, some fillers in these coatings of significant thickness can be comparable to their zinc phosphate counterparts.Research limitations/implications -The anticorrosive properties of the coatings studied can also be tested in paints by means of atmospheric exposure, for instance, with the aid of a Florida test. Practical implications -The findings are helpful towards applications in the formulations of anticorrosive coatings of significant thickness that offer an effective barrier mechanism. Originality/value -The research presents the results of the properties of a whole range of industrially employed fillers and pigments contained in paints. Based on this study, the formulation of steel protecting coatings can be optimised.
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